A review of literature relating to pollution control reveals that the general approach is to reactively clean waste streams entering the environment. If too much of one pollutant or another is detected or being discharged, the tendency has been to focus on the source of the pollutant. For the most part gaseous streams are treated to reduce the pollutants prior to entering the atmosphere.
It has been disclosed to treat atmospheric air directed into a confined space to remove undesirable components therein. However, there has been little effort to treat pollutants which are already in the environment; the environment has been left to its own self-cleansing systems.
References are known which disclose proactively cleaning the environment. U.S. Pat. No. 3,738,088 discloses an air filtering assembly for cleaning pollution from the ambient air by utilizing a vehicle as a mobile cleaning device. A variety of elements are disclosed to be used in combination with a vehicle to clean the ambient air as the vehicle is driven through the environment. In particular, there is disclosed ducting to control air stream velocity and direct the air to various filter means. The filter means can include filters and electronic precipitators. Catalyzed postfilters are disclosed to be useful to treat non-particulate or aerosol pollution such as carbon monoxide, unburned hydrocarbons, nitrous oxide and/or sulfur oxides, and the like.
Another approach is disclosed in U.S. Pat. No. 5,147,429. There is disclosed a mobile airborne air cleaning station. In particular this patent features a dirigible for collecting air. The dirigible has a plurality of different types of air cleaning devices contained therein. The air cleaning devices disclosed include wet scrubbers, filtration machines, and cyclonic spray scrubbers.
The difficulty with devices disclosed to proactively clean the atmospheric air is that they require new and additional equipment. Even the modified vehicle disclosed in U.S. Pat. No. 3,738,088 requires ducting and filters which can include catalytic filters.
DE 40 07 965 C2 to Klaus Hager discloses a catalyst comprising copper oxides for converting ozone and a mixture of copper oxides and manganese oxides for converting carbon monoxide. The catalyst can be applied as a coating to a self-heating radiator, oil coolers or charged-air coolers. The catalyst coating comprises heat resistant binders which are also gas permeable. It is indicated that the copper oxides and manganese oxides are widely used in gas mask filters and have the disadvantage of being poisoned by water vapor. However, the heating of the surfaces of the automobile during operation evaporates the water. In this way, continuous use of the catalyst is possible since no drying agent is necessary. Responsive to the difficulties associated with devices which proactively treat the atmosphere, the Assignee herein in U.S. patent application Ser. No. 08/410,445 filed on Mar. 24, 1995, U.S. patent application Ser. No. 08/589,182 filed Jan. 19, 1996, and U.S. patent application Ser. No. 08/589,030 filed Jan. 19, 1996, each incorporated herein by reference, disclosed apparatus in related methods for treating the atmosphere by employing a moving vehicle. In preferred embodiments a portion of the surface of the engine or cabin cooling system (e.g. the radiator, air-conditioning condenser, etc.) is coated with a catalytic or adsorption composition. Additionally, the fan associated with the engine cooling system can operate to draw or force air into operative contact with the radiator. Pollutants contained within the air such as ozone, hydrocarbons and/or carbon monoxide are then catalytically converted to non-polluting compounds (e.g., oxygen, water and carbon dioxide).
The Assignee herein also has pending U.S. patent application Ser. No. 08/412,525 filed on Mar. 29, 1995, incorporated herein by reference, which discloses devices and methods for proactively treating the atmosphere catalytically by employing a stationary object such as selected surfaces of an automobile at rest, a billboard, an air conditioning unit and the like coated with a catalytic composition.
In addition, International Publication No. WO 98/02235 of the Assignee herein discloses a process of catalytically activating the surface of a heat exchange device such as a motor vehicle radiator while retaining the heat exchange properties of the device. The method enables the catalytic treatment of the atmosphere by converting pollutants contained therein to less harmful materials while allowing the radiator to perform its function normally. A polymeric protective coating which is stable up to temperatures of about 100.degree. C. may be employed to retard degradation and inactivation of the catalyst.
The application of a catalyst or absorbent composition to the surface of a substrate such as a radiator of a motor vehicle presents problems such as the exposure of the composition to relatively high concentrations of contaminants which can deleteriously affect the functioning of the composition. Such contaminants include solid or vaporized particulates, corrosive compounds such as salts and oxides of nitrogen, sulfur and the like. Contact of the composition with such contaminants can result in masking, fouling and/or poisoning. In addition, water (and contaminants contained therein) can be a source of degradation and can also decrease the activity and useful life of catalyst and adsorbent compositions.
It would therefore be a significant advance in the art of reducing atmospheric pollution to employ catalytic and adsorptive composition coated devices for the treatment of the atmosphere to remove pollutants contained therein wherein the composition is protected against those contaminants commonly encountered in the atmosphere which can adversely affect performance of the composition. It would be a further advance in the art if the composition could be protected from contaminants at from ambient temperatures up to about several hundred degrees centigrade. It would be still a further advance in the art if the composition could be protected from water especially liquid water.